Improved process op obtaining glycerine from soap-makers  spent lyes



Zlbriirti fitters palm onto,

BENJAMIN r. A'BBITT, or NEW YORK/N; Y.

Letters Patent No. 107,324, dated September 13, 1870.

IMPROVED PROCESS OF OBTAINING GLYCERINE FROM SOAP-MAKERS SPENT LYES.

The Schedule referred to in these Letters Patent and making part ofthe same- To all whom 1' It may concern Be it known that I, BENJAMIN '1; BABBITT, of the city, county, and State of New York, have invented a new Process of Obtaining Glycerinc from Soap-makers Spent-Lyes; and I do hereby declare that the following is a full, clear,-and exact description of the same. i

In the manuiiicture of soap it has heretofore been customary, after the .boiling of the tallow or fat with the alkaline solution, to effect the separation from the soup of the spent lye containing the glycerinc, which has been'cxtractcd from vthe fallow or fat, by means oi'a solution of common salt.-

Some attempts have-been made to extract the glycerine from this solution, but no method that has been .hcrctofin'e tried has been made commercially profitable, and the solution has been commonly thrown away to waste.

In my invention, instead of using common salt to ciicct the separation of the soap from the spent lye, I

use caustic alkali, by which the glycerine is taken up and I afterward boil the resulting liquor with fresh tallow or fat, by which the alkali is absorbed, leaving a liquor, consisting of glycerine and water, and from which I obtain the glycerine by evaporating the water.

The process is conducted'in the following manner:

After the soap'has been formed in the usual way, by boiling thcinllow or fat with an alkaline solution, 1 pump into, or otherwise introduce among it in the boiler, which may be an ordinary kettle, a sufficient quantity of solution of caustic soda, of a density of about 35 of Baniiis hydromctcr, to take upall the water and glycol-inc.

On the contents of the boiler being allowed to cool,

the liquor, composed of water, caustic s'oda,,and glyccrine, falls to the bottom, leaving the soap floating upon its surihcc.

The quantity of the caustic-soda solution introduced to the soap is immaterial, provided it be sufficient, as an excessive quantity can do no injury. Instead of the caustic alkali being introduced in solution, it may be introduced in powder, with the same effect.

The liquor left in the boiler may beuscd over and over again several times in the same manner, above described, as the caustic-alkaline solution in separating the water and glycerine from other charges of soap in the same or other boilers, and, for this purpose, may be pumped directly from the boiler in which it has been used into anotherboiler, or be drawn off into a suit-able receptacle, and pumped therefrom back into the sam'ekettlaafter a new batch of soaphas been produced therein; but, previous to every repetition of its use, it should be bleached by throwing into it a quantity of lime, reduced by-water to a pasty state, and afterward decanting it from the dime.

The use of this liquor in this way may be'repeated until, by testing a small quantity, by boiling with a suitable quantity of fresh tallow', to absorb'all of its alkali, thcrcsulting solution of glyceriug and water has a specific gravity 01- about-30 of Baums hydrom'eter, when the said liquor may be reduced with water to a suitable alkaline strength, to enable its alkali to be readily absorbed by tallow or fat, and be then boiled with tallow or fat, till what is left of :it shows no alkali by test, and, therefore, contains nothing but glycei'ine and water.-

On evaporating the water from this by heat the glycerine remains. I

In the last-mentioned operation-of boiling with tub low or fat, a suilicient quantity of the tallow or fat must be used, and additions may be made until there is sufficient to absorb all the alkali, and it is obvious that any excess of tallow or fat will do no injury. The tallow or fat may be afterward converted into soup in the usual way.

\Vhat I claim as my inventiom ninl (b'siru in socure by Letters Patent, is-- The extraction of glycerine from soap-makers sponb lye, by treatment with caustic alkali, and subsequent boiling with tallow or fat, substantially as herein described.

B. T. BABBITT.

Witnesses FRED. HAYNES, R. E. RABEAU. 

